An electronic device with anti-theft protection includes an alarm unit, a mercury connector, and a microprocessor connected therebetween. The mercury connector includes a body containing mercury, and first and second leads arranged on the body. The microprocessor includes a first signal terminal and a second signal terminal. The first signal terminal is connected to the first lead. The second signal terminal is connected to the second lead. When the microprocessor has entered the anti-theft mode, if the electronic device is moved, the first lead connects to the second lead via the mercury and forms a circuit path from the first signal terminal to the second signal terminal. The microprocessor starts the alarm unit to generate an alarm.